In a March 10 consent agreement with E.I. du Pont de Nemours and Co. (DuPont), the Environmental Protection Agency (EPA) lowered its standard for drinking water contamination with the toxic Teflon chemical perfluorooctanoic acid (PFOA) from 0.5 parts per billion (ppb) to 0.4 ppb for people in the vicinity of a DuPont plant in Parkersburg, West Virginia.

The new EPA-DuPont agreement does not reflect the most recent science and falls far short of what is required to protect thousands of families who live near the DuPont facility. The more scientists study PFOA, the stronger the case becomes for extremely strict limits on human exposure. PFOA appears to be following the pattern set by other persistent, bioaccumulating toxic chemicals like PCBs, DDT, mercury and lead. In those cases, trace amounts once considered safe were later found to present significant health risks, particularly to the young. It is important to learn from these experiences and adopt protective standards early on, to prevent avoidable harm that will almost certainly be discovered in the future.

There is a clear and consistent trend emerging in the scientific literature, showing that even very low exposures of PFOA can affect the normal functioning of the hormone system and, by extension, human reproduction. Scientists from the Centers for Disease Control and Prevention (CDC) have found that PFOA contaminates the bodies of virtually all Americans tested, with a median level of 4 ppb. Significantly, two recent peer-reviewed studies found that PFOA, at 4 to 5 ppb in human blood, adversely affected fertility in women and sperm viability in men. Most of these people are exposed to PFOA from consumer products and sources other than tap water. This suggests that people drinking PFOA-contaminated tap water are very likely to attain blood levels well above those associated with the adverse effects cited in the studies.

Even if people were not already contaminated with PFOA, the EPA’s new Provisional Health Advisory would not protect them from attaining very high blood levels of the compound. Data generated by scientists from the University of Pennsylvania show that drinking water contaminated with PFOA at 0.4 ppb, as the consent agreement allows, would easily lead to human blood levels as high as 40 ppb. This is well above the median exposure value in most extensive study of PFOA’s impact on people, the 69,000-person Parkersburg study, carried out by an independent panel of academic scientists and paid for by DuPont, that indicates PFOA causes significant dose dependent effects on the endocrine system, including decreased levels of reproductive hormones. These findings are consistent with earlier animal studies.

The weight of the evidence argues for a much lower guidance value for PFOA in drinking water, along the lines of the 0.04 ppb standard in New Jersey, or even lower.

EPA has based the new consent agreement on a Provisional Health Advisory for PFOA issued on January 8, 2009. At that time, the agency said "The relevant period of exposure for the Health Advisory is a short-term exposure." Clearly, EPA did not intend the level of 0.4 ppb to serve as a long-term safe drinking water benchmark.

The fact is that there is no such thing as short-term drinking water exposure. People drink tap water every day. PFOA persists in the environment, and thus in water supplies, for hundreds of years. Except in a very few states, most water utilities rely on EPA’s Health Advisory as authoritative guidance on how much PFOA contamination can be tolerated. In the absence of a long-term standard, EPA’s Provisional Health Advisory will be used to justify long-term exposures to PFOA, even though it was not intended to stand as a long-term drinking water advisory and it is not protective for such exposures. Applying this short-term health advisory to long-term exposure to contaminated water directly contradicts both sound science and EPA’s own principles of risk assessment and risk management.

EPA’s arrangement with DuPont would likely give a false sense of security to thousands of West Virginians and Ohioans whose drinking water has been polluted by toxic discharges from the Parkersburg facility. PFOA contamination has been found in ambient waters and drinking water sources in at least 11 states, potentially leaving large number of municipal water system users at risk.

We urge you to direct the appropriate officials at EPA to conduct a comprehensive risk assessment for long-term exposure to PFOA. We hope you will develop a fully protective national drinking water standard that takes into account the bioaccumulative properties of this cancer-causing, developmentally disruptive toxicant.